Author Affiliations
Abstract
1 School of Biomedical Science, Huaqiao University, Quanzhou 362021, China
2 College of Engineering, Huaqiao University, Quanzhou 362021, China
We propose a laser speckle contrast imaging method based on uniting spatiotemporal Fourier transform. First, the raw speckle images are entirely transformed to the spatiotemporal frequency domain with a three-dimensional (3D) fast Fourier transform. Second, the dynamic and static speckle components are extracted by applying 3D low-pass and high-pass filtering in the spatiotemporal frequency domain and inverse 3D Fourier transform. Third, we calculate the time-averaged modulation depth with the average of both components to map the two-dimensional blood flow distribution. The experiments demonstrate that the proposed method could effectively improve computational efficiency and imaging quality.
uniting spatiotemporal Fourier transform laser speckle contrast image fluctuation modulation 3D Fourier transform 
Chinese Optics Letters
2024, 22(1): 011701
Author Affiliations
Abstract
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
Multiphoton microscopy is the enabling tool for biomedical research, but the aberrations of biological tissues have limited its imaging performance. Adaptive optics (AO) has been developed to partially overcome aberration to restore imaging performance. For indirect AO, algorithm is the key to its successful implementation. Here, based on the fact that indirect AO has an analogy to the black-box optimization problem, we successfully apply the covariance matrix adaptation evolution strategy (CMA-ES) used in the latter, to indirect AO in multiphoton microscopy (MPM). Compared with the traditional genetic algorithm (GA), our algorithm has a greater improvement in convergence speed and convergence accuracy, which provides the possibility of realizing real-time dynamic aberration correction for deep in vivo biological tissues.
multiphoton microscopy 1700-nm window adaptive optics covariance matrix adaptation evolution strategy 
Chinese Optics Letters
2023, 21(5): 051701
Author Affiliations
Abstract
1 MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
2 Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
3 Department of Ophthalmology and Optometry, School of Medical Technology and Engineering, Fujian Medical University, Fuzhou 350004, China
We present for the first time, to the best of our knowledge, a needle probe for photoacoustic viscoelasticity (PAVE) measurements at a depth of 1 cm below the sample surface. The probe uses a gradient index rod lens, encased within a side-facing needle (0.7 mm outer diameter), to direct excitation light (532 nm) and detection light (1325 nm) focused on the sample, collecting and directing the returned detection light in a spectral domain low coherence interferometry system, which allows for obtaining optical phase differences due to photoacoustic oscillations. The feasibility of needle probe for PAVE depth characterization was investigated on gelatin phantoms and in vitro biological tissues. The experimental results in an in vivo animal model predict the great potential of this technique for in vivo tumor boundary detection.
needle probe photoacoustic viscoelasticity measurement depth-resolved mechanical phase delay mechanical interface 
Chinese Optics Letters
2022, 20(8): 081701
Author Affiliations
Abstract
1 State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
2 Department of Cardiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China
3 The Affiliated Hospital of Tianjin Chinese Medical Institute, Tongji University, Shanghai 200092, China
4 Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
5 Jinan Institute of Quantum Technology, Jinan 250101, China
6 Collaborative Innovation Center of Light Manipulation and Applications, Shandong Normal University, Jinan 250358, China
Atherosclerotic cardio-cerebral vascular disease is the most common disease that threatens human health. Many researches indicated that oxidatively modified low-density lipoprotein (ox-LDL) is a key pathogenic factor of atherosclerosis. Here, we report the change of the secondary structure of ox-LDL caused by photoirradiation in an optofluidic resonator. The content ratios of amphipathic α-helices and β-sheets of ox-LDL are changed under laser beam illumination, resulting in an increasing binding rate of ox-LDL and ox-LDL antibodies. Our findings may provide a potential way for clinical atherosclerosis treatment and prompt recovery rate of atherosclerotic cardio-cerebral vascular disease by optical technology and immunotherapy.
atherosclerosis ox-LDL optofluidic resonator photoirradiation 
Chinese Optics Letters
2022, 20(3): 031702
Author Affiliations
Abstract
1 School of Communication & Information Engineering, Shanghai University, Shanghai 200444, China
2 Academy for Engineering & Technology, Fudan University, Shanghai 200433, China
3 State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200433, China
4 Center for Biomedical Engineering, Fudan University, Shanghai 200433, China
Fluorescence microscopy technology uses fluorescent dyes to provide highly specific visualization of cell components, which plays an important role in understanding the subcellular structure. However, fluorescence microscopy has some limitations such as the risk of non-specific cross labeling in multi-labeled fluorescent staining and limited number of fluorescence labels due to spectral overlap. This paper proposes a deep learning-based fluorescence to fluorescence (Fluo-Fluo) translation method, which uses a conditional generative adversarial network to predict a fluorescence image from another fluorescence image and further realizes the multi-label fluorescent staining. The cell types used include human motor neurons, human breast cancer cells, rat cortical neurons, and rat cardiomyocytes. The effectiveness of the method is verified by successfully generating virtual fluorescence images highly similar to the true fluorescence images. This study shows that a deep neural network can implement Fluo-Fluo translation and describe the localization relationship between subcellular structures labeled with different fluorescent markers. The proposed Fluo-Fluo method can avoid non-specific cross labeling in multi-label fluorescence staining and is free from spectral overlaps. In theory, an unlimited number of fluorescence images can be predicted from a single fluorescence image to characterize cells.
deep learning conditional generative adversarial network fluorescence image image translation 
Chinese Optics Letters
2022, 20(3): 031701
Author Affiliations
Abstract
1 Department of Biomedical Science & Engineering, Institute of Integrated Technology, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
2 Center for Bionics, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
Laser speckle imaging is a common technique to monitor blood flow. The fluctuations in speckle intensity can be related to the blood flow by calculating the speckle contrast, the ratio between the standard deviation of speckle fluctuations and the average intensity. However, this simple statistic calculation is easily affected by motion artifacts. In this study, we applied sample entropy analysis instead of calculating standard deviations of the speckle fluctuations. Similar to the traditional method, sample entropy-based speckle contrast increases linearly with flow rate but was shown to be more immune to sudden movements during an upper arm occlusion test.
laser speckle imaging sample entropy speckle contrast blood flow monitoring motion artifact 
Chinese Optics Letters
2022, 20(1): 011702
Author Affiliations
Abstract
1 School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510006, China
2 National Innovation Center for Advanced Medical Devices, Shenzhen 518131, China
3 GBA Branch of Aerospace Information Research Institute, Chinese Academy of Sciences, Guangzhou 510530, China
4 School of Biomedical Engineering, Sun Yat-sen University, Guangzhou 510006, China
5 State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
6 State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
7 School of Artificial Intelligence, Guilin University of Electronic Technology, Guilin 541004, China
In this paper, we propose and demonstrate a dual-beam delay-encoded Doppler spectral domain optical coherence tomography (OCT) system for in vivo measurement of absolute retinal blood velocity and flow with arbitrary orientation. The incident beam is split by a beam displacer into two probe beams of the single-spectrometer spectral domain OCT system with orthogonal polarization states and an optical path length delay. We validate our approach with a phantom and in vivo experiments of human retinal blood flow, respectively.
optical coherence tomography ocular perfusion optic nerve head ophthalmology 
Chinese Optics Letters
2022, 20(1): 011701
Author Affiliations
Abstract
1 Department of Biomedical Engineering, College of Engineering, Peking University, Beijing 100871, China
2 College of Future Technology, Peking University, Beijing 100871, China
3 Ultrasonography, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
Photoacoustic imaging (PAI) with a handheld linear ultrasound (US) probe is widely used owing to its convenient and inherent dual modality capability. However, the limited length of the linear probe makes PAI suffer from the limited view. In this study, we present a simple method to substantially increase the view angle aided by two US reflectors. Both phantom and in vivo animal study results have demonstrated that the imaging quality can be greatly improved with the reflector without sacrificing the imaging speed.
photoacoustic imaging limited view multimodal imaging 
Chinese Optics Letters
2021, 19(12): 121702
Author Affiliations
Abstract
1 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
2 IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
Localized wavefront aberrations would introduce artifacts in biomedical imaging, which, however, are often neglected, as their compensations are at the cost of the field-of-view. Here, we show rarely reported local artifacts in two-photon imaging of dendrites beneath blood vessels in a mouse brain in vivo and interpret the phenomena via numerical simulations. The artifacts of divided parallel structures are found to be induced by coma and astigmatism, resulting from sample tilting and the cylinder shape of vasculatures, respectively. Different from that in single-photon microscopy, such artifacts in nonlinear microscopy show unique characteristics and should be recognized for proper interpretation of the images.
biomedical imaging two-photon microscopy wavefront aberration artifacts of dendrites mouse cortex 
Chinese Optics Letters
2021, 19(12): 121701
Author Affiliations
Abstract
Department of Biomedical Engineering, City University of Hong Kong, Hong Kong 999077, China
Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ treatment. These versatile small biomedical robots are expected to realize direct access to the tumor or disease site for precise treatment, which requires real-time and high-resolution in vivo tracking as feedback for the microrobots’ actuation and control. Among current biomedical imaging methods, photoacoustic imaging (PAI) is presenting its outstanding performances in the tracking of microrobots in the human body derived from its great advantages of excellent imaging resolution and contrast in deep tissue. In this review, we summarize the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective, we also provide some insight into the future of PAI technology in clinical applications.
photoacoustic imaging PACT OR-PAM microrobots tracking clinical applications 
Chinese Optics Letters
2021, 19(11): 111701

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